1. Field of the Invention
The present invention relates to an oil hydraulic cylinder for use in industrial purposes or chairs, and more particularly, to an oil hydraulic cylinder configured to smoothly lift a moving object (seat part) without shaking movement thereof when the moving object is lifted by hydraulic pressure and to prevent the moving object from being rotated unnecessarily.
2. Description of the Related Art
As is well known, oil hydraulic cylinders used for jacks for vehicles and other industrial purposes or beauty parlor chairs are equipped with an adjusting lever for lifting or lowering a moving object.
By way of example, a widely used beauty parlor chair having a seat part where a beautician sits for hair cutting is lifted and lowered by a lifting mechanism. The beauty parlor chair is vertically operated by a direct manipulation of an oil hydraulic cylinder, or a combination of an oil cylinder and a parallel link.
A beauty parlor chair using the method of vertically moving a seat part by an oil cylinder is disposed with an oil hydraulic cylinder at a base pedestal thereof, and the oil hydraulic cylinder is mounted with a seat part at a distal end portion thereof to adjust the height of the seat part in response to vertical movement of a piston rod (an operation rod) disposed at the oil hydraulic cylinder side.
In other words, in case of using an oil hydraulic cylinder, a foot is used to repeatedly tread on an adjusting lever to lift a seat part. When the seat part reaches a desired position through the above process, operation of stepping on the adjusting lever is stopped to stop lifting the seat part. Thereafter, when the adjusting lever is trod to the extreme lower end to return the seat part to an original position, the seat part is lowered to come back to the original position.
Meanwhile, as illustrated in FIGS. 1 and 2, where a beauty parlor chair is lifted by a combination method of an oil hydraulic cylinder and a parallel link as patented by Korea Patent No. 344036, a lift mechanism 230 disposed at an upper part of a base pedestal 221 includes a frame 231 defined on an upper side of the base pedestal 221, a first parallel link 250 rotatably connected at one end thereof to the frame 231 and rotatably connected at the other end thereof to a connecting member of link bracket 232, a second parallel link 260 rotatably connected at one end thereof to a pedestal 233 and rotatably connected at the other end thereof to the link bracket 232, a pedestal 233 for supporting a seat part (not shown), a third link rod 270 for connecting the first parallel link 250 to the second parallel link 260 and an oil hydraulic cylinder 280 mounted at the frame 231 and connected to the second parallel link 260.
The first parallel link 250 consists of a first link rod 251 and a first pull rod 252, where the first link rod 251 is rotatably connected at one side thereof to the frame 231 via an axle 253, and the first pull rod 252 is disposed underneath the first link rod 251 and rotatably connected at one side thereof to the frame 231 via an axle 255.
Furthermore, the first link rod 251 is rotatably connected at the other side thereof to a link bracket 232 via an axle 254, and the first pull rod 252 is rotatably connected at the other side thereof to the link bracket 232 via an axle 256.
The second parallel link 260 includes a second link rod 261 and a second pull rod 262, where the second link rod 261 is rotatably connected at one distal end thereof to a pedestal 233 via an axle 263, and the second pull rod 262, being disposed underneath the second link rod 261, is rotatably connected at one distal end thereof to the pedestal 233 via an axle 266. The second link rod 261 is rotatably connected at the other distal end thereof to the link bracket 232 via an axle 264, and the second pull rod 262 is rotatably connected at the other distal end thereof to the link bracket 232 via an axle 266.
The third link rod 270 is rotatably connected at one distal end thereof via an axle 271 to a tip end disassociated at a predetermined distance from an axle 254 relative to the other distal end side of the first link rod 251, and is rotatably connected at the other distal end thereof to the second link rod 261.
The oil hydraulic cylinder 280 composed of a cylinder tube 281 and a piston rod 282 is connected to an oil hydraulic pump (not shown) via a pipe, and is reduced or increased in pressure thereof from the oil hydraulic pump (not shown) by manipulation of an adjusting lever (not shown). In other words, a base pedestal of the cylinder tube 281 is rotatably connected to the frame 231 via a cylinder axle 283 and a distal end portion of the piston rod 282 is rotatably connected to the second link rod 261 via an axle 284.
In the conventional lift mechanism 230 thus described, when a seat part (to be described later) is lifted upwards from a lowest position as illustrated in FIG. 2, by way of example, when a beautician manipulates an adjusting lever (not shown), an oil hydraulic pump (not shown) applies an oil pressure to the oil hydraulic cylinder 280 by manipulation of an adjusting lever (not shown) to elongate the piston rod 282, whereby the second parallel link 260 is rotated upwards about the axles 264 and 266.
At this time, the third link rod 270 pulls up the first parallel link 250 in response to the rotating operation of the second parallel link 260, whereby the first parallel link 250 is rotated upwards about the axles 253 and 255, enabling to allow the pedestal 233 to move upwards maintaining a horizontal state.
Although the second parallel link 260 is rotated counterclockwise about the axles 264 and 266 to allow the pedestal 233 to move forwards at a central position thereof as a result of the pedestal 233 moving upwards, the first parallel link 250 is clockwise rotated about the axles 253 and 255 in cooperation with the rotating operation of the second parallel link 260, whereby the link bracket 232 is moved backwards as much as the pedestal 233 that has moved forwards at the center position thereof, maintaining the center position of the pedestal 233 as is.
Meanwhile, when a seat part 224 is moved downwards, by way of example, when an adjusting lever (not shown) is trodden or pressed, an oil hydraulic pump (not shown) reduces the pressure of the oil hydraulic cylinder 280 to shorten the lengthen the piston rod 282. As a result, the second parallel link 260 is rotated downwards about the axles 264 and 266
At this time, the third link rod 270 pulls down the first parallel link 250 in response to rotating operation of the second parallel link 260 such that the first parallel link 250 is rotated downwards about the axles 253 and 255 and as a result, the pedestal 233 is moved downwards with a horizontal state thereof maintained.
Although the second parallel link 260 is rotated clockwise about the axles 264 and 266 to allow the central position of the pedestal 233 to move backwards in response to the pedestal 233 moving downwards, the first parallel link 250 is rotated counterclockwise about the axles 253 and 255 in cooperation with the rotating operation of the second parallel link 260 whereby the link bracket 232 is moved forwards as much as the central position of the pedestal 233 moving backwards, thereby preventing the central position of the pedestal 233 from being disoriented.
However, there is a drawback in the lifting operation by the conventional oil hydraulic cylinder thus described in that a seat part is lifted by repeated treading of an adjusting lever to reach a predetermined height during which a man on the seat part feels discomfort at every step of pressed stage of the adjusting lever.
There is another drawback in a cylinder type in that a seat part itself is unnecessarily rotated, preventing the seat part from being secured at a desired direction.
These kinds of drawbacks found in a chair may be somewhat considered less problematic if compared with those that might happen in industrial oil hydraulic cylinders or oil hydraulic jacks for vehicles. These problems may cause industrial disasters in the industrial fields.